A disposable conductivity sensor probe

Abstract

The present application relates to a disposable conductivity sensor probe, including: a probe electrode and a measuring circuit, which are integrated into a PCB circuit board. The PCB circuit board body adopts a sealed structure, and the probe electrode is exposed to facilitate contact with seawater, and is used to measure the conductivity of seawater; the probe electrode includes two voltage measurement electrode pairs, a current measurement electrode pair and an excitation electrode. The measuring circuit includes: an excitation signal generating circuit, a voltage measurement circuit, and a current measurement circuit. Through this application, it is achieved to reduce production costs and meet the high precision and reliability requirements of conductivity measurement.

Description

Technical Field

[0001] The present application relates to the field of data measurement technology, and in particular to a disposable conductivity sensor probe used for measuring ocean hydrological data. Background Art

[0002] In the field of oceanographic data measurement, the expendable conductivity temperature and depth profiling system (XCTD) has been widely used. With its real-time and large-area coverage, this device has important application value in ocean observation. At present, the core component of the mainstream expendable conductivity temperature and depth profiling system on the market is the conductivity sensor probe.

[0003] Existing conductivity sensor probes usually adopt electromagnetic induction design, mainly composed of electromagnetic probe and measurement circuit board. Based on the electromagnetic induction measurement principle, the electromagnetic probe is composed of two magnetic rings of the same size, with coils of different numbers of turns wrapped around the outside of the magnetic rings, serving as excitation coils and induction coils respectively. These magnetic rings are combined with the outer structure of the conductivity cell and the whole is encapsulated by injection molding. Traditional conductivity sensors and probes are separated, and the forms of probes are also varied, basically in the form of cylindrical flow guide tubes. The probe has high cost, high measurement accuracy and complex process.

[0004] Although the design of this sensor is mature, its production process is complex and the manufacturing process relies heavily on manpower, which directly leads to an increase in cost. At the same time, since XCTD is a disposable device, low-cost production capacity has become an important factor in market competition. However, the existing technology has significant deficiencies in achieving mass production and reducing manufacturing costs. Summary of the invention

[0005] The embodiment of the present application provides a disposable conductivity sensor probe to at least reduce production costs and meet the high precision and reliability requirements of conductivity measurement.

[0006] To achieve the above-mentioned purpose, an embodiment of the present application provides a disposable conductivity sensor probe, comprising: a probe electrode and a measuring circuit, which are integrated into a PCB circuit board, the PCB circuit board body adopts a sealed structure, and the probe electrode is exposed to contact seawater, and is used to measure the conductivity of seawater; the probe electrode comprises two voltage measurement electrode pairs, a current measurement electrode pair and an excitation electrode;

[0007] The measuring circuit comprises:

[0008] An excitation signal generating circuit is electrically connected to a controller, receives a voltage signal generated by the controller, and outputs an excitation signal, wherein the excitation signal is connected to the excitation electrode via a signal output terminal;

[0009] A voltage measurement circuit, electrically connected to the two voltage measurement electrode pairs and the controller, for measuring a voltage difference between the two voltage measurement electrode pairs to perform voltage measurement;

[0010] The current measuring circuit is electrically connected to the current measuring electrode pair and the controller, and measures the current of the sampling resistor via a sampling resistor to obtain the current flowing between the current measuring electrode pair.

[0011] In some embodiments, the excitation signal generating circuit includes:

[0012] A voltage follower U7, whose input end is connected to the controller;

[0013] A signal amplification module, electrically connected to the voltage follower U7, the signal amplification module includes an operational amplifier U6A and an operational amplifier U6B, both of which are used to generate voltage signals EXCE_SIG- and EXCE_SIG+ with the same amplitude and positive and negative to each other based on the voltage signal EXCE_IN output by the voltage follower U7;

[0014] The switch module U5 can switchably connect the operational amplifier U6A and the operational amplifier U6B to generate the excitation signal.

[0015] Based on the above structure, the excitation signal generating circuit of the present application passes the voltage signal of the controller through the voltage follower U7 to ensure the stability of the signal and provide sufficient driving force, and then uses the signal amplification module for differential configuration to generate positive and negative signals with the same amplitude, and performs frequency switching through the switch module U5 to output a symmetrical square wave as the excitation signal.

[0016] In some embodiments, the voltage measurement circuit includes:

[0017] An instrument amplifier is electrically connected to the two voltage measurement electrode pairs to obtain a voltage difference signal between the two voltage measurement electrode pairs, amplify the voltage difference signal, and then output a measurement square wave;

[0018] A switch module U10, electrically connected to the two instrument amplifiers;

[0019] A first integral filter module, including an integral filter U11A and an integral filter U11B, which are electrically connected to the switch module U10, wherein the integral filter U11A obtains the positive half of the measurement square wave through the switch module U10 and outputs it as a first positive level signal, and the integral filter U11B obtains the negative half of the measurement square wave through the switch module U10 and outputs it as a first negative level signal;

[0020] The differential amplifier U12 is electrically connected to the first integral filter module and the controller to obtain the first positive level signal and the first negative level signal and output an arithmetic mean thereof.

[0021] Based on the above structure, the voltage measurement circuit of the present application performs signal acquisition, processing and average value calculation through an instrument amplifier and a first integral filter module. The back-end signal is selected by the switch module U10, and the positive half and negative half of the measurement square wave are respectively extracted by the integral filter U11A and the integral filter U11B and smoothly converted into DC level signals, namely, the first positive level signal and the first negative level signal. Finally, the difference between the two signals is calculated by the differential amplifier U12 to obtain the voltage difference between the two pairs of measuring electrodes.

[0022] In some embodiments, the current measurement circuit includes:

[0023] A sampling resistor R21 is connected in series with the current measuring electrode pair; the current across the sampling resistor R21 is the same as the current of the conductivity cell, so the current of the conductivity cell can be measured by calculating the current obtained by measuring the voltage across the resistor; an operational amplifier U1, a switch module U2, a second integral filter module and a differential amplifier U4, wherein:

[0024] The operational amplifier U1 is electrically connected to the sampling resistor R21, and is used to perform primary amplification on the voltage signal at both ends of the sampling resistor to increase the signal amplitude;

[0025] The switch module U2 is electrically connected to the operational amplifier U1 and is used to switch the signal path;

[0026] A second integral filter module, comprising an integral filter U3A and an integral filter U3B, the two being connected to the switch module U2 respectively, the integral filter U3A obtaining the positive half of the voltage signal at both ends of the sampling resistor via the switch module U2 and outputting it as a second positive level signal, the integral filter U3B obtaining the negative half of the voltage signal at both ends of the sampling resistor via the switch module U2 and outputting it as a second negative level signal;

[0027] The differential amplifier U4 is electrically connected to the second integral filter module and the controller to obtain the second positive level signal and the second negative level signal and output the arithmetic mean thereof. The difference between the second positive level signal and the second negative level signal is used by the controller to calculate the current thereof according to the resistance value of the sampling resistor R21.

[0028] Based on the above structure, the current measurement circuit of the present application realizes accurate current detection through a high-precision sampling resistor, and provides high-quality current signal measurement results.

[0029] In some embodiments, the probe electrode includes 7 electrodes arranged at equal intervals, wherein 4 electrodes are voltage measurement electrode pairs, 2 electrodes are current measurement electrode pairs, and 1 electrode is an excitation electrode.

[0030] In some embodiments, the voltage measurement electrode has an electrode area smaller than the excitation electrode and the current measurement electrode.

[0031] In some of the embodiments, the measuring circuit is soldered by SMT.

[0032] In some of the embodiments, the electrode is made of copper or copper-gold plating technology, and the desired shape is directly produced through a PCB corrosion process, including coating a resist on the copper sheet, then exposing and developing, and finally removing the unprotected copper by chemical corrosion to form an electrode pattern.

[0033] In some of the embodiments, the PCB circuit board is made of a four-layer epoxy resin sheet with copper foil on one side, wherein the upper surface layer and the lower surface layer are grounded by large-area copper plating to form a shielding layer, the probe electrode is arranged on the upper surface or the lower surface of the PCB circuit board, and the electrode routing is arranged in the middle layer of the PCB circuit board.

[0034] In some of the embodiments, the sealing structure is made of epoxy resin glue or organic silicone glue.

[0035] Compared with the related art, the disposable conductivity sensor probe provided in the embodiment of the present application adopts an integrated structure of the probe and the measuring circuit board, wherein the probe part adopts an electrode probe, and is integrated with the measuring circuit board based on the circuit board manufacturing, replacing the existing probe in the form of a cylindrical flow guide tube. Through structural optimization and simplified process flow, this solution significantly reduces production costs and provides higher economy and efficiency for large-scale manufacturing;

[0036] In addition, the overall system design of the disposable conductivity sensor probe of the present application focuses on signal stability and anti-interference capability, and can meet the high-precision and reliability requirements of conductivity measurement.

[0037] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0039] Figure 1 is a circuit schematic diagram of an excitation signal generating circuit according to an embodiment of the present application;

[0040] Figure 2 is a circuit schematic diagram of a voltage measurement circuit according to an embodiment of the present application;

[0041] Figure 3 is a circuit schematic diagram of a current measurement circuit according to an embodiment of the present application;

[0042] Figure 4 is a structural reference diagram of a disposable conductivity sensor probe according to an embodiment of the present application;

[0043] Figure 5 yes Figure 4 A partial enlarged view of the probe part. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0045] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0046] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0047] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0048] This embodiment provides a disposable conductivity sensor probe. Figures 1 to 4 1 is a partial circuit or overall schematic diagram of a disposable conductivity sensor probe according to an embodiment of the present application. Figures 1 to 4 As shown, the disposable conductivity sensor probe includes: a probe electrode and a measuring circuit, which are integrated into a PCB circuit board. The PCB circuit board body adopts a sealing structure, and the sealing structure adopts epoxy resin glue or organic silicone. The probe electrode is exposed to contact seawater and is used to measure the conductivity of seawater; the measuring circuit includes components such as an excitation signal generating circuit, a voltage measuring circuit, and a current measuring circuit. Those skilled in the art can understand that Figures 1 to 3 The circuit structure of the disposable conductivity sensor probe shown in the figure does not constitute a limitation to the disposable conductivity sensor probe, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0049] Combine the following Figures 1 to 4 The following is a detailed introduction to the various components of the disposable conductivity sensor probe:

[0050] Combined with reference Figure 5 As shown, the probe electrode includes two voltage measurement electrode pairs, a current measurement electrode pair and an excitation electrode; in this embodiment, the probe electrode includes 7 electrodes arranged at equal intervals, such as Figure 5 As shown, the electrode spacing is 2 mm, wherein 4 electrodes are voltage measurement electrode pairs, electrode 2, electrode 3, electrode 5, and electrode 6 are voltage measurement electrode pairs, and voltage measurement is performed by measuring the voltage difference between electrode 2, electrode 3, and between electrode 5 and electrode 6, and 2 electrodes are current measurement electrode pairs, as shown in FIG. Figure 5 Among the electrodes 1 and 7, one electrode is an excitation electrode. Figure 5 The middle electrode 4 is used for the excitation signal output terminal of the excitation signal generating circuit. The electrode area of ​​the voltage measuring electrode is smaller than that of the excitation electrode and the current measuring electrode. The current measuring electrode and the excitation electrode are 2 mm wide and 15 mm long, and the voltage measuring electrode is 0.5 mm wide and 15 mm long.

[0051] refer to Figure 1 As shown, in the above embodiment, the excitation signal generating circuit is electrically connected to a controller, receives the voltage signal DAC_EXCE generated by the controller, and outputs an excitation signal, the excitation signal is a 20khz square wave with a square wave peak of 50mV, and the excitation signal is connected to the excitation electrode via the signal output terminal EI_IN; specifically, the excitation signal generating circuit includes:

[0052] The voltage follower U7, whose input end is connected to the controller, is used to improve the signal driving capability and ensure the signal stability;

[0053] A signal amplification module, electrically connected to the voltage follower U7, the signal amplification module includes an operational amplifier U6A and an operational amplifier U6B, both of which are used to generate voltage signals EXCE_SIG- and EXCE_SIG+ with the same amplitude and positive and negative to each other based on the voltage signal EXCE_IN output by the voltage follower U7;

[0054] The switch module U5, whose D pin is switched at a frequency of 20khz, is switchably connected to the operational amplifier U6A and the operational amplifier U6B to generate the excitation signal. Optionally, the switch module U5 is a 20khz high-speed switch, whose SA pin and SB pin are respectively connected to the operational amplifier U6B and the operational amplifier U6A to obtain the voltage signal, and the D pin can frequently switch the connection with the SA pin and the SB pin under the control of the controller's EXCE_TRIG signal. The specific selection of the high-speed switch is not specifically limited here, and those skilled in the art can make adaptive adjustments according to specific signal processing needs.

[0055] Based on the above structure, the excitation signal generating circuit of the present application passes the voltage signal of the controller through the voltage follower U7 to ensure the stability of the signal and provide sufficient driving force, and then uses the signal amplification module for differential configuration to generate positive and negative signals with the same amplitude. The switch module U5 performs frequency switching to output a symmetrical square wave as the excitation signal. The two-stage amplifier and the high-speed switch realize the precise output of positive and negative symmetrical square waves, ensuring the stability of the excitation signal during the conductivity measurement process. The high-speed switch is used to avoid signal waveform distortion. The square wave has good edge clarity and symmetry. The circuit adopts a differential design to enhance the anti-interference ability, ensure that the excitation signal is not affected by external noise, and provide a square wave signal with stable frequency and strong symmetry as an excitation source, thereby ensuring the accuracy and stability of the conductivity measurement and improving the measurement accuracy.

[0056] refer to Figure 2 As shown, in the above embodiment, the voltage measurement circuit is electrically connected to the two voltage measurement electrode pairs and the controller, and is used to measure the voltage difference between the two voltage measurement electrode pairs to perform voltage measurement. Specifically, the voltage measurement circuit includes:

[0057] Two instrument amplifiers U8 and U9 are electrically connected to the two voltage measurement electrode pairs to obtain the voltage difference signal between the two voltage measurement electrode pairs, amplify it and then output a measurement square wave;

[0058] The switch module U10 is electrically connected to the two instrument amplifiers U8 and U9; optionally, the switch module U10 is a high-speed switch. The specific selection of the high-speed switch is not specifically limited here, and those skilled in the art can make adaptive adjustments according to specific signal processing needs.

[0059] A first integral filter module, including an integral filter U11A and an integral filter U11B, which are electrically connected to the switch module U10, wherein the integral filter U11A obtains the positive half of the measurement square wave through the switch module U10 and outputs it as a first positive level signal, and the integral filter U11B obtains the negative half of the measurement square wave through the switch module U10 and outputs it as a first negative level signal;

[0060] The differential amplifier U12 is electrically connected to the first integral filter module and the controller to obtain the first positive level signal and the first negative level signal and output an arithmetic mean thereof.

[0061] Based on the above structure, the voltage measurement circuit of the present application performs signal acquisition, processing and average value calculation through the instrument amplifier and the first integral filter module to extract the voltage difference signal between the two pairs of electrodes 2 and 3 and electrodes 5 and 6. Each instrument amplifier has a high input impedance and a high common-mode rejection ratio, which can amplify weak voltage difference signals and suppress common-mode noise, so that the measurement accuracy can still remain stable at low signal levels. The back-end signal is selected by the switch module U10 according to the preset logic, and the positive half and the negative half of the measurement square wave are respectively extracted by the integral filter U11A and the integral filter U11B and smoothly converted into DC level signals, namely the first positive level signal and the first negative level signal, so as to improve the stability of the signal and reduce the influence of noise and high-frequency interference on the measurement results. Finally, the difference between the two signals is calculated by the differential amplifier U12 to obtain the voltage difference between the two pairs of measurement electrodes, thereby avoiding the influence of single electrode errors and improving the reliability of voltage measurement.

[0062] refer to Figure 3 As shown, in the above embodiment, the current measurement circuit is electrically connected to the current measurement electrode pair and the controller, and the current flowing between the current measurement electrode pair is obtained by measuring the current of the sampling resistor through a sampling resistor. Specifically, the current measurement circuit includes:

[0063] The sampling resistor R21 is connected in series with the current measuring electrode pair; the current across the sampling resistor R21 is the same as the current of the conductivity cell, so the current of the conductivity cell can be measured by calculating the current obtained by measuring the voltage across the resistor; the sampling resistor R21 is a high-precision, low-temperature drift resistor.

[0064] The operational amplifier U1 is electrically connected to the sampling resistor R21 and is used to perform primary amplification on the voltage signal at both ends of the sampling resistor to increase the signal amplitude;

[0065] The switch module U2 is electrically connected to the operational amplifier U1 and is used to switch the signal path. Its working principle is the same as that of the switch module U10 of the voltage measurement circuit, and will not be described in detail here. In the figure, the tail end of the switch module U2 is also provided with a filter capacitor C5 and a filter capacitor C6 for removing high-frequency noise;

[0066] A second integral filter module, comprising an integral filter U3A and an integral filter U3B, the two being connected to the switch module U2 respectively, the integral filter U3A obtaining the positive half of the voltage signal at both ends of the sampling resistor via the switch module U2 and outputting it as a second positive level signal, the integral filter U3B obtaining the negative half of the voltage signal at both ends of the sampling resistor via the switch module U2 and outputting it as a second negative level signal;

[0067] The differential amplifier U4 is electrically connected to the second integral filter module and the controller to obtain the second positive level signal and the second negative level signal and output the arithmetic mean thereof. The difference between the second positive level signal and the second negative level signal is used by the controller to calculate the current thereof according to the resistance value of the sampling resistor R21. The calculation can be implemented based on Ohm's law and will not be described in detail here.

[0068] Based on the above structure, the current measurement circuit of the present application realizes accurate current detection through a high-precision sampling resistor, and provides high-quality current signal measurement results.

[0069] In order to achieve structural optimization and simplify the process flow, the measurement circuit adopts SMT patch welding, which has a high degree of automation, can improve production efficiency, reduce manual intervention, and ensure the consistency of welding quality. The electrode adopts copper deposition or copper deposition gold plating process, and the required shape is directly made through the PCB corrosion process, including coating the copper skin with resist, then exposing and developing, and finally removing the unprotected copper by chemical corrosion to form an electrode pattern. Based on this, it not only provides a good electrical connection, but also significantly improves the corrosion resistance and stability of the electrode, which can effectively deal with the problem of electrode oxidation caused by long-term storage.

[0070] In addition, the PCB circuit board adopts a four-layer epoxy resin sheet with copper foil attached to one side. The thickness of the copper foil can be 35 microns, 70 microns, or 105 microns. The embodiment of the present application selects a sheet with a copper foil thickness of 70 microns, wherein the upper surface layer and the lower surface layer are grounded by large-area copper plating to form a shielding layer, which effectively reduces electromagnetic interference and improves the stability and reliability of the circuit. The probe electrode is arranged on the upper surface or the lower surface of the PCB circuit board, and the electrode routing is arranged in the middle layer of the PCB circuit board, which is the 2nd and 3rd layers of the PCB circuit board in this embodiment, which can reduce external interference to the signal.

[0071] In summary, the overall system design of the disposable conductivity sensor probe of the present application focuses on signal stability and anti-interference capability, and can meet the high-precision and reliability requirements of conductivity measurement.

[0072] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A disposable conductivity sensor probe, characterized in that: include: The probe electrode and the measuring circuit are integrated into a PCB circuit board. The main body of the PCB circuit board adopts a sealed structure, and the probe electrode is exposed to facilitate contact with seawater; The probe electrodes include a current measuring electrode pair, two voltage measuring electrode pairs and an excitation electrode; The measuring circuit comprises: An excitation signal generating circuit is electrically connected to a controller, receives a voltage signal generated by the controller, and outputs an excitation signal, wherein the excitation signal is connected to the excitation electrode via a signal output terminal; A voltage measurement circuit, electrically connected to the two voltage measurement electrode pairs and the controller, for measuring a voltage difference between the two voltage measurement electrode pairs to perform voltage measurement; The current measuring circuit is electrically connected to the current measuring electrode pair and the controller, and measures the current of the sampling resistor via a sampling resistor to obtain the current flowing between the current measuring electrode pair.

2. The disposable conductivity sensor probe according to claim 1, characterized in that: The excitation signal generating circuit comprises: A voltage follower U7, whose input end is connected to the controller; A signal amplification module, electrically connected to the voltage follower U7, the signal amplification module includes an operational amplifier U6A and an operational amplifier U6B, both of which are used to generate voltage signals with the same amplitude and positive and negative values ​​based on the voltage signal output by the voltage follower U7; The switch module U5 can switchably connect the operational amplifier U6A and the operational amplifier U6B to generate the excitation signal.

3. The disposable conductivity sensor probe according to claim 2, characterized in that: The voltage measurement circuit comprises: An instrument amplifier is electrically connected to the two voltage measurement electrode pairs to obtain a voltage difference signal between the two voltage measurement electrode pairs, amplify the voltage difference signal, and then output a measurement square wave; A switch module U10, electrically connected to the two instrument amplifiers; A first integral filter module, including an integral filter U11A and an integral filter U11B, which are electrically connected to the switch module U10, wherein the integral filter U11A obtains the positive half of the measurement square wave through the switch module U10 and outputs it as a first positive level signal, and the integral filter U11B obtains the negative half of the measurement square wave through the switch module U10 and outputs it as a first negative level signal; The differential amplifier U12 is electrically connected to the first integral filter module and the controller to obtain the first positive level signal and the first negative level signal and output an arithmetic mean thereof.

4. The disposable conductivity sensor probe according to claim 2 or 3, characterized in that: The current measurement circuit comprises: A sampling resistor R21, connected in series with the current measuring electrode pair; An operational amplifier U1, electrically connected to the sampling resistor R21; A switch module U2, electrically connected to the operational amplifier U1; A second integral filter module, comprising an integral filter U3A and an integral filter U3B, the two being connected to the switch module U2 respectively, the integral filter U3A obtaining the positive half of the voltage signal at both ends of the sampling resistor via the switch module U2 and outputting it as a second positive level signal, the integral filter U3B obtaining the negative half of the voltage signal at both ends of the sampling resistor via the switch module U2 and outputting it as a second negative level signal; The differential amplifier U4 is electrically connected to the second integral filter module and the controller to obtain the second positive level signal and the second negative level signal and output the arithmetic mean thereof. The difference between the second positive level signal and the second negative level signal is used by the controller to calculate the current thereof according to the resistance value of the sampling resistor R21.

5. The disposable conductivity sensor probe according to any one of claims 1 to 4, characterized in that: The probe electrode includes 7 electrodes arranged at equal intervals.

6. The disposable conductivity sensor probe according to claim 5, characterized in that: The electrode area of ​​the voltage measuring electrode is smaller than that of the excitation electrode and the current measuring electrode.

7. The disposable conductivity sensor probe according to claim 5, characterized in that: The measuring circuit is soldered by SMT.

8. The disposable conductivity sensor probe according to claim 5, characterized in that: The electrode adopts copper plating or copper plating gold plating process.

9. The disposable conductivity sensor probe according to any one of claims 1 to 4, characterized in that: The PCB circuit board adopts a four-layer epoxy resin plate with copper foil on one side, wherein the upper surface layer and the lower surface layer form a shielding layer, the probe electrode is arranged on the upper surface or the lower surface of the PCB circuit board, and the electrode routing is arranged in the middle layer of the PCB circuit board.

10. The disposable conductivity sensor probe according to any one of claims 1 to 4, characterized in that: The sealing structure adopts epoxy resin glue or organic silica gel.

Images